A smoke detector generally uses an ionization chamber containing a radioactive ion source that is coupled to a high input impedance operational amplifier. However when operating at elevated temperatures the input leakage current of the operational amplifier increases. This affects overall performance of the ionization chamber smoke detection function. Also the ionization chamber contains radioactive materials that during manufacture necessitate compliance with regulatory requirements pertaining to storing and handling of these radioactive materials. The smoke detectors having ionization chambers containing a radioactive ion source are increasingly coming under stronger government regulatory control due to the radioactive element (ion source) contained therein.